This invention generally relates to a composition having co-continuous interconnecting channel morphology comprising three componentsxe2x80x94two polymers (i.e. components A and B) and a particle (i.e. component C) wherein the channels consist mainly of component B and the majority of component C resides in the channels. This co-continuous interconnecting channel morphology is designed to control the gas transmission rate through the composition. Components A and B are generally immiscible within each other. In addition, one criteria for selecting component C and components A and B may be based on component C preferential affinity for component B over component A. Another criteria for selecting components B and C may be based on the capability of the combination of components B and C to either increase or decrease the gas transmission properties of component A. For example, component C may be a desiccant particle. In one embodiment, the composition of the present invention is useful in the manufacture of shaped articles such as containers, films and sheets for applications requiring a tailored moisture vapor transmission rate.
Polymeric structures having tailored transmission characteristics are suitable, for example, for flexible and for rigid packages. For example, flexible films having tailored moisture vapor transmission (xe2x80x9cMVTxe2x80x9d) characteristic may be used in packages such as pouches, bags and wraps and in a wide variety of application, including food preservation. In another example, polymeric structures having tailored gas transmission characteristics may also be used in such applications as filtration for solids, the ultra filtration of colloidal matter, as diffusion barriers or separators in electrochemical cells. In yet another example, polymeric structures having tailored MVT characteristics may also be used in applications requiring permeability to water vapor but not liquid water for applications such as garments including rain coats and outerwear and camping equipment. Such films may be also used for filter cleaning, surgical dressings bandages and in other fluid transmissive medical applications. One method that has been used to tailor the transmission properties of a polymeric structure is by creating a microporous structure in the polymer. For example, a blend of solvent and polymer are extruded, the solvent is leached out of the extruded material and then the material is stretched to obtain a desired porosity. Typically, these micropores are void spaces but also may be subsequently filled with material, in an additional step.
The present invention discloses a composition having co-continuous interconnecting channel morphology. In one embodiment, these co-continuous interconnecting channels may be designed to control the amount and/or rate of migration of the desired property (e.g., gases from any surface of the composition through the interior of the composition to any other surface). Furthermore, these co-continuous interconnecting channels through which the desired substance is permitted to travel are occupied by a polymer (e.g., hydrophilic agents) that controls the percolation through the composition. This polymer is mixed with at least another polymer (i.e. major component) and a particle that form the interconnecting channel morphology and a percolation path.